MongoDB里findOne()是不是相当于SQL中LIMIT 1

Question

看到这个关于SQL中加入 LIMIT 1 是否会更快的问题，/q/10100000001...
老牛我就想起了mongodb里的 findOne

db.collection.findOne(query)

不知道是不是跟SQL的一样，还是说跟db.collection.find().limit(1)一样？

Answer 1

The limit() function in mongoDB is the same as the limit in sql. The limit() function in mango is also used after the find() function.

Answer 2

Although the implementation mechanism is not much different from db.collection.find().limit(1) 差距太多，但用起来和 db.collection.find().limit(1),

findOne 是 找到第一条,返回数据，然后关闭游标cursor 这些操作一气喝成
db.collection.find().limit(1) is to first return the cursor, obtain the required data, and then close the cursor

The specific implementation still depends on the client...

Answer 3

One meaning